Roller chain tensioning device

Abstract

A roller chain tensioning device includes a pair of low friction chain engaging blocks that are held selectively together by a flexible strap and fastener device. The blocks include formed surfaces for loosely receiving the side plates of the chain and for roller engagement by the chain rollers. The chain flights are received with the rollers in moving contact with the guide blocks while the chain side plates are loosley and freely received by opposed grooves, opposite to the roller engaging surfaces. The blocks are provided with opposed roller engaging surfaces of different size to facilitate operation with chains having rollers of different size. The strap and fastener enable selective adjustment of the blocks toward or away from one another thereby adjust tension along the engaged chain flights.

I claim: 
     
       1. A tensioning device for roller chains which are comprised of links formed by paired side plates joined in a continuous length by rollers and with oppositely movable first and second flights connected in a drive mechanism, the tensioning device comprising: a pair of the tensioning guide blocks;   a roller engaging surface on each guide block for engaging the chain rollers;   the tensioning guide blocks including openings extending therethrough substantially transverse to the roller engaging surfaces;   a tensioning connector joining the guide blocks for selective adjustment toward and away from each other with one roller engaging surface on one guide block engaging chain roller along the first flight, and the roller engaging surface on the remaining tensioning guide block engaging chain rollers along the second flight;   wherein the tensioning connector is comprised of a strap extending through the openings and being freely slidable therein; and   a fastener on the tensioning connector operable to (a) secure the tensioning connector with the guide blocks positioned at a selected distance apart to impart a selected tension along the first and second flights of the chain, and to (b) release the tensioning connector to enable the guide blocks to be separated beyond the selected distance and thereby release the selected tension along the first and second flights.   
     
     
       2. The tensioning device for roller chains as claimed by claim 1 wherein the guide blocks each include recessed side plate receiving surfaces spaced to opposite sides of the roller engaging surface and formed into the guide block to provide clearance between the chain side plates and the guide block and with the chain rollers engaging the roller engaging surface. 
     
     
       3. The tensioning device for roller chains as claimed by claim 1 wherein the guide blocks are formed of a low friction coefficient plastic material. 
     
     
       4. The tensioning device for roller chains as claimed by claim 1 wherein the guide blocks include convex arcuate surfaces and wherein the roller engaging surfaces are located on the convex arcuate surfaces. 
     
     
       5. The tensioning device for roller chains as claimed by claim 1 wherein: the guide blocks each include recessed side plate receiving surfaces spaced to opposite sides of the roller engaging surface, the recessed side plate receiving surfaces being formed into the guide block to provide clearance between the chain side plates and guide block with rollers of the chain engaging the roller engaging surface; and   the roller engaging surfaces and recessed side plate receiving surfaces are formed as convex arcuate surfaces on the guide blocks.   
     
     
       6. The tensioning device for roller chains as claimed by claim 1 wherein: the guide blocks are formed of a low friction coefficient plastic material;   the guide blocks each include recessed side plate receiving surfaces spaced to opposite sides of the roller engaging surface, the recessed side plate receiving surfaces being formed into the guide block to provide clearance between the chain side plates and guide block with rollers of the chain engaging the roller engaging surface; and   the roller engaging surfaces and recessed surfaces are formed along convex arcs on the guide blocks.   
     
     
       7. The tensioning device for roller chains as claimed by claim 1 wherein: the guide blocks each include a pair of opposed convex surfaces with a first roller engaging surface on one convex surface adapted to receive a chain of a first size, and a second roller engaging surface on the remaining convex surface adapted to receive a chain of a second size.   
     
     
       8. The tensioning device for roller chains as claimed by claim 1 wherein the fastener is attached to one end of the strap and includes a gripping element for slidably receiving the remaining strap end and for selectively gripping the strap along its length.   
     
     
       9. The tensioning device for roller chains as claimed by claim 8 wherein the strap is comprised of woven nylon strands. 
     
     
       10. A tensioning device for roller chains which are comprised of links formed by paired side plates joined in a continuous length by rollers and with oppositely movable first and second flights connected in a drive mechanism, the tensioning device comprising: a pair of tensioning guide blocks;   a roller engaging surface on each guide block for engaging the chain rollers;   recessed side plate receiving surfaces spaced to opposite sides of the roller engaging surface of each guide block, the recessed side plate receiving surfaces being formed into the guide block to provide clearance between the chain side plates and guide block with rollers of the chain engaging the roller engaging surface;   wherein the guide blocks each include a pair of opposed convex surfaces with a first roller engaging surface on one convex surface dimensioned to receive a chain of a first size, and a second roller engaging surface on the remaining convex surface dimensioned to receive a chain of a second size; and   a tension means joining the guide blocks for selective adjustment toward and away from each other.   
     
     
       11. The tensioning device for roller chains as claimed by claim 10 wherein: the guide blocks are formed of a low friction coefficient plastic material.   
     
     
       12. The tensioning device for roller chains as claimed by claim 10 wherein the guide blocks include convex arcuate surfaces and wherein the roller engaging surfaces are located on the convex arcuate surfaces. 
     
     
       13. A roller chain tensioning guide block, for roller chain comprised of links formed by paired side plates, comprising: a guide block body;   wherein the guide block body includes a pair of opposed convex surfaces with a first roller engaging surface on one convex surface dimensioned to receive a chain of a first size, and a second roller engaging surface on the remaining convex surface dimensioned to receive a chain of a second size; and   recessed side plate receiving surfaces formed into the body and spaced to opposite sides of the roller engaging surface, the recessed side plate receiving surfaces being formed into the guide block to provide clearance between the chain side plates and guide block with rollers of the chain engaging the roller   
     
     
       14. The roller chain tensioning guide block of claim 13 wherein: the guide block body is formed of a low friction coefficient plastic material; and   wherein the roller engaging surfaces and recessed surfaces are formed along convex arcs on the guide block body.